Sam Altman and OpenAI (the firm he founded) have opened his talks for his possible return. A possible outcome could be adding Altman to the transitional OpenAI board.
It seemed that although Microsoft was open to hiring Altman and others from OpenAI, it may have been more of a headache legally. What happened behind closed doors to prompt his ousting is not fully known. It might make sense to hit the reset button, work out the problems and go forward. By the way, Microsoft owns 49% of OpenAI.